GRASSES OF IOWA. 131 



mucrpnate or awned at the apex. Stamens 3. (Dedicated to the Rev. 

 Dr. Henry Muehlenberg, a distinguished American botanist of the early 

 part of the last century.) 



About 60 species according to Bentham and Hooker; the same 

 number according to Hackel, of which Heller lists 37 species north of 

 .Mexico. Thirty-five species are reported for Mexico and Central 

 America. 



KEY TO THE SPECIES OF MUHLENBERGIA. 



Flowering glume not awned, often acuminate. 



Empty glumes acute, about % as long as the flowering glume. 



— .M. sobolifera. x 



Empty glumes acuminate, about 3 mm. long, about equalling the 

 flowering glume M. mexicana . " 



Empty glumes awned, about 5 mm. long, nearly twice the length of 

 the flowering glume M. glomerata . z 



Flowering glume awned. 



Awn usually twice the length of the glume. 



Empty glumes minute M. diffusa.^ 



Empty glumes about one-half as long as flowering glume. 



— .M. Wildenovii . 5 



Empty glumes about equalling the flowering glume. .M. sylvatica.*> 



Awn 3-4 times as long as the glume, second empty glume distinctly 

 3-awned, Cultivated M . gracilis.' 



1. MUHLENBERGIA SOBOLIFERA. 



Muhlenbergia sobolifera Tr'm. Unifl. 189.1824. Watson and Coulter. 

 Gray. Man. Bot. 643. 1890. (6th ed.) Scribner. Grasses of Tenn. Bull. 

 Univ. Tenn. Agrl. Exp. Sta. 7: 67. /. 82. 1894. Vasey Contr. U. S. Nat. 

 Herb. 3: 68. 



Muhlenbergia sobolifera (Muhl.)Trin. Beal. Grasses of N. A. 2: 244. 

 1896. Nash in Britton and Brown. 111. Fl. 1: 142. /. 320. 1896. 



